/*
 * Copyright (c) 2008, Ivan Appel <ivan.appel@gmail.com>
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer. 
 * - Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution. 
 *
 * Neither the name of Ivan Appel nor the names of any other jThinker
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package oss.jthinker.util;

/**
 * Associated trigger. Gets some value as initial and then is updated
 * accordingly with peer's changes.
 * 
 * @author iappel
 * @param T trigger state type
 */
public class AssociatedTrigger<T> extends Trigger<T> implements TriggerListener<T> {
    private final Trigger<T> _peer;

    /**
     * Creates a new AssociatedTrigger instance.
     * 
     * @param initialState initial state
     * @param peer peer to get subsequent values
     */
    public AssociatedTrigger(T initialState, Trigger<T> peer) {
        super(initialState);
        peer.addStateConsumer(this);
        _peer = peer;
    }
    
    /**
     * Sets trigger's value to peer's value.
     * @inheritDoc
     */
    public void stateChanged(TriggerEvent<? extends T> event) {
        if (event.getSource() == _peer) {
            setState(event.getState());
        }
    }
}
